What is this and what does it do?

[280ZWarrior]

I'm wondering about the BCDD myself lately ( as in do you really need that?)

Never heard of that before. I did a search for it and it seems like it could be part of my rpm problem. However, I haven't found anything on adusting it...

sblake01-Do you have any further knowledge of adjusting the BCDD??

Thanks in advance,

Mike

[TomoHawk]

the BCDD (Boost-Controlled Deceleration Device) injects a little air when you let off the gas pedal to prevent a cloud of smoke coming out the tailpipe. It is electronically controlled, and can't be adjusted. Maybe it can be disconnected & removed, but I don't know if it would affect the way the engine runs. I suppose if it leaked air, it might raise the RPM.

[Grim]

I said it was oncars with manual trannies only becouse that is what the factory service manual said.

[sblake01]

Grim, I stand corrected. I just did some reading. FSM, page ET-3. Manual transmission only. But, one more correction: Tomohawk, the BCDD can be adjusted. See page EC-7 & EC-8 in the FSM.

[DatsunZsRule]

Also under "Engine Tune Up" in the FSM look at page ET-9 It does say (Manual Transmission Models Only) for Dash Pot Adj.

[sblake01]

What makes this all seem rather strange is that the original post is about an automatic car that was converted to a manual. And it has the dashpot and hence my original statement. The FSM says manual trans only for the dashpot, but my 'junkyard research' says that that is not true.

[280ZWarrior]

Grim, I stand corrected. I just did some reading. FSM, page ET-3. Manual transmission only. But, one more correction: Tomohawk, the BCDD can be adjusted. See page EC-7 & EC-8 in the FSM.

If the instructions from the FSM aren't too long for the adjustment of the BCDD, could you post them? I am still in the process of finding a '78 FSM at a reasonable price and only have the chilton manual.

Thanks again,

Mike

[Grim]

I have never been around an automatic z so I didn't know the part was on them as well. I'll have to make a note in the manual. Could save on questions some day. I can't think of any reason why the idle would be different. Just a guess but could the auto tranny just drag the motor down slightly?

[sblake01]

It took me a while to get it together but here it is:

[DatsunZsRule]

The rare times I've seen Automatic 280Z's do not have the Dash Pot and the Factory Service Manual is not going to lie either so I have to agree it's got to be on Manuals only. If your Automatic models have it then possibly the previous owners did some parts swapping from a manual model? My guess anyways.

Also the B.C.D.D. on an automatic model is different from a manual model. I can't remember if the adjustment procedure is the same.

[sblake01]

The service manual is not going to lie? Well, I don't think it's lying but there are many inconsistencies when you deal with these cars. Take a look at these two scans, both from FSM's. One makes no mention of transmission type and the other does.

[DatsunZsRule]

Yeah, I hear ya. They sure don't make it clear do they?

Well, we know it's purpose and how to adjust it if necessary I guess thats all that counts